Oleg is great. In this case we're actually going the opposite direction (going back to a concrete data structure). His stream fusion stuff is really cool, but

Oleg is great. In this case we're actually going the opposite direction (going back to a concrete data structure). His stream fusion stuff is really cool, but I don't know of any popular libraries that have incorporated unfortunately. I think the Scala fs2 stream library was interested in trying to implement some of the ideas some years back, but I think they ended up not having the time or energy.